1. Technical Field
The present invention relates to electrooptic devices suitable for use in displaying various information.
2. Related Art
General liquid crystal devices have an illuminating unit on the back of a liquid-crystal display panel for transmission display. The general liquid crystal devices have used a constant-intensity light source both in light places and in dark places irrespective of extraneous light.
However, humans feel even low-luminance light bright because the pupils of humans' visual sense dilate in dark places. Nevertheless, illuminating units illuminate the liquid-crystal display panel at constant luminance all the time. Accordingly, humans feel the illumination too bright in dark places to see the display screen. Moreover, illuminating units use the same constant-luminance light source as that for dark places even in very light places where the luminance of the reflected light is higher than that of transmitted light, causing wasteful power consumption.
JP-A-2005-121997 discloses a method for controlling the backlight of a liquid-crystal display device in which the backlight is automatically controlled only when the illuminance around the liquid-crystal display panel changes evenly. JP-A-6-18880 and JP-A-6-28881 disclose liquid crystal displays in which the illuminance of the display screen is automatically controlled according to a light control profile on the basis of the illuminance of ambient light sensed.
However, the above-mentioned JP-A-2005-121997 describes merely a method for automatically controlling the back light. This method has the problem that if the method is applied to a liquid crystal device having multicolor filters equipped with a backlight, it is impossible to automatically control the backlight in consideration of contrast and color matching.
JP-A-6-18880 and JP-A-6-28881 have the problem that the light control profile is not suitable for humans' visual sense.